Investigating the effect of herbal extracts of oak, tea and chamomile onAspergillus in cultured shrimps in laboratory conditions

Introduction: Today, proliferation and breeding of aquatics, particularly shrimp,is of great importance due to the presence of proteins and mineral rich materialsas well as short duration of its proliferation and breeding. Unfortunately, in someconditions due to the presence of some fungi such as Aspergillus, irreparablelosses are imposed to shrimp farming industry. Today, the desire to use medicinalherb to improve diseases led this study to investigate the effect of three medicinalherb extracts including tan bark, green tea and chamomile on pathogenesis ofAspergillus in shrimp.Methods: The Aspergillus samples were prepared from Scientific and IndustrialResearch Organization of Iran and Pasteur Institute of Iran. They weremaintained in Potato Dextrose Agar (PDA) gradient culture for ۵-۷ days at ۲۵ ˚C.Mycelium causes disruption in the culture and reduces the impact of the extracts.To remove them from fungal suspension, the suspension was filtered using glasswool. Then, light transmittance from the suspension was measured using aspectrophotometer device at a wavelength of ۵۳۰ nm. The light transmittance of۹۰% is required to obtain a suspension with approximately ۱۰۶ fungal spores perml. Five test tubes including yeast extract (YES) were prepared for each extract and totally ۱۵ medium cultures were obtained. The extracts with concentrationsof ۲۰۰, ۴۰۰, ۶۰۰, ۸۰۰, ۱۰۰۰ ppm with Tween were added to yeast extract (YES)medium. The tubes were vortexed to maintain the suspension and the extracts for۶۰ seconds and they were visually assessed up to ۴ days in terms of degree ofgrowth or lack of growth. The contents of the tubes were then filtered usingWhatman Grade ۴۲ filter paper and mycelial dry weight was obtained by aspecial scale.Results: Among ۳ studied extracts, chamomile extract had the best inhibitoryeffect on Aspergillus and tea extract had the weakest inhibitory effect. Theinhibitory effect of tan bark extract was near to the effect of chamomile extract sothat they both had approximately similar effect on fungal growth atconcentrations of ۶۰۰ and ۱۰۰۰ ppm. The impact of tan bark extract at theconcentration of ۲۰۰ ppm on inhabitation of fungal growth had better, with alittle difference, from chamomile extract.Discussion and Conclusion: Due to the proper effects of chamomile extract atconcentrations of ۸۰۰ and ۱۰۰۰ ppm and tan bark extract at concentrations of ۶۰۰and ۱۰۰۰ ppm, which both showed the best and proper in vitro inhibitory effecton Aspergillus and on mycelial dry weight, their usage is recommended fortreatment and prevention of aspergillosis.

Keywords:

Tan Bark , Chamomile , Green Tea , Aspergillus , Shrimp